Abnormalities of thyroid function tests in adult patients with nephrotic syndrome

Transcription

1 International Journal of Research in Medical Sciences Karethimmaiah H et al. Int J Res Med Sci Oct;4(10): pissn eissn Research Article DOI: Abnormalities of thyroid function tests in adult patients with nephrotic syndrome Hareeshababu Karethimmaiah 1 *, Vijaya Sarathi 2 1 Department of Nephrology, Vydehi Institute of Medical Sciences and Research Center, Bangalore, India 2 Department of Endocrinology, Vydehi Institute of Medical Sciences and Research Center, Bangalore, India Received: 09 September 2016 Accepted: 14 September 2016 *Correspondence: Dr. Hareeshababu Karethimmaiah, drharri@yahoo.com Copyright: the author(s), publisher and licensee Medip Academy. This is an open-access article distributed under the terms of the Creative Commons Attribution Non-Commercial License, which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. ABSTRACT Background: Nephrotic syndrome is well-known cause of thyroid dysfunction in children; however, there is limited data on this issue in adults, especially regarding natural course of thyroid abnormalities. Methods: atients with nondiabetic nephropathies were included in the study and evaluated with thyroid function tests at diagnosis and every 2-3 monthly. Age and sex matched healthy volunteers constituted the control group. Results: The study included 39 patients with newly diagnosed nephrotic syndrome and 39 controls. When compared to the control group, patients with nephrotic syndrome had significantly higher thyroid stimulating hormone and significantly lower total thyroxine, total triiodothyronine, free thyroxine and free triiodothyronine levels. Eighteen patients had remission at last follow-up (18.3±3.4 months) and those with remission had improvement in thyroid function tests. Anti thyroperoxidase antibody tended to be more common in nephrotic syndrome patients and among patients with remission, elevated antibodies was associated with persistence of hypothyroidism. Conclusions: Nephrotic syndrome in adult patients is significantly associated with abnormalities in thyroid function tests. All these abnormalities improve with remission of nephrotic syndrome. atients with elevated thyroid stimulating hormone and anti-thyroperoxidase antibody levels are more likely to progress to overt hypothyroidism and should be closely followed-up or replaced with levothyroxine. Keywords: Nephrotic syndrome, roteinuria, Hypothyroidism, Anti thyroperoxidase antibodies INTRODUCTION Nephrotic syndrome (NS) is a common cause of massive proteinuria and is associated with loss of multiple binding proteins like thyroid binding globulin (TBG), corticosteroid binding globulin and vitamin D binding globulin. 1,2 Urinary loss of thyroid binding globulin is accompanied with loss of thyroxine (T4) and triiodothyronine (T3). 3-6 This leads to decrease in serum total thyroxine (TT4) and serum total triiodothyronine (TT4) concentrations and increases the demand on thyroid gland to produce more T4. This increased demand is reflected by increase in the elevation of thyroid stimulating hormone (TSH), although not always above the upper limit of normal. 4,5 Many studies have documented thyroid abnormalities in children with NS. 4-7 In children, association of thyroid abnormalities with NS may help to identify the latter condition at an earlier stage. Elevation of TSH in newborn screening programs often leads to diagnosis of congenital NS. 8,9 However, there is limited data on thyroid abnormalities in adults with NS. More importantly, the natural history of thyroid abnormalities in adult patients with NS is not well studied. It has been documented that abnormalities in thyroid functions could be normalised by LT4 replacement. On the other hand, few studies have concluded that thyroid abnormalities are transient and does not require replacement with LT4. 4,11 International Journal of Research in Medical Sciences October 2016 Vol 4 Issue 10 age 4300

2 Hence, it is not clear whether patients with NS with subclinical hypothyroidism should receive replacement with L-thyroxine. It would be important to know the course of thyroid functions in adult patients with NS and identify any predictors of persistence of hypothyroidism in them. Hence, we have studied the thyroid function abnormalities and predictors of persistence of thyroid abnormalities in adults with NS. METHODS The study was conducted between January 2012 and December 2015 at department of Nephrology in a tertiary health care center at Bangalore. The study was approved by institutional ethics committee and a written informed consent was obtained by all participants. All patients aged more than 18 years, who presented with nephrotic syndrome, were included in the study. Nephrotic syndrome was defined as 24-h urinary protein excretion >3.5 g/1.73m 2 or spot urinary protein creatinine ratio >2.0. atients with acute sickness, pregnancy, lactation, diabetes mellitus and previously diagnosed patients with hypothyroidism were excluded from the study. Age and sex matched healthy volunteers constituted the control group. At diagnosis of NS, all participants were subjected for serum total protein, albumin and globulin, 24-h urinary protein excretion, spot urinary protein creatinine ratio, thyroid function tests including TSH, TT4, TT3, FT3, FT4 and anti-thyroperoxidase antibody (anti-to) level. Additional investigations such as renal biopsy, serum complement 3, antinuclear antibody, HBsAg, anti HCV and anti HIV etc were performed as per the standard protocol at our institution to evaluate an adult with new onset NS. Among 39 patients, fifteen had focal segmental glomerulonephritis, thirteen had minimal change disease, five had membranous nephropathy and one had membraneoproliferative glomerulonephritis whereas in the rest renal biopsy was not done since patients deferred the procedure. All patients received treatment with immunosuppressive drugs as per the standard protocols. atients were followed up every 1-3 monthly with spot urinary protein creatinine ratio, serum creatinine and serum albumin and 2-3 monthly with thyroid function tests. atients with spot urinary protein creatinine ratio <2.0 were considered to have remission of NS. artial remission was defined as spot urinary protein creatinine ratio and complete remission as <0.2. atients were replaced with LT4 only if TSH 20 µiu/ml. Thyroid function tests, serum creatinine, serum albumin, urinary protein, urinary creatinine were analysed using Unicel DxC 600 Synchron, Beckman Coulter Ireland Inc. Normal reference range for TSH, TT4, TT3, FT3, FT4 and anti TO were µIU/ml, µg/dl, ng/ml, pg/ml, ng/dl and 9 IU/ml. Statistical analysis was performed using SSS version 20 (SSS software, Chicago IL, USA). Continuous variables are mentioned as mean ±SD and categorical variables are mentioned as percentages. Continuous variables between two groups were analysed using independent t test and categorical variables using chi-square test. Variables at diagnosis of NS and at last follow-up we compared using paired t test. A p value less than <0.05 was considered significant. RESULTS Thirty nine patients presented with newly diagnosed NS. The mean age of the study population was 34.89±9.14 years and was not significantly different from that of controls (n=39). When compared to the age and sex matched control group, patients with NS had significantly higher TSH and significantly lower TT4, TT3, FT3 and FT4 (Table 1). In NS group, sixteen (41.02%) patients had normal TSH ( µiu/ml), four (10.25%) had more than 10 µiu/ml whereas the rest (19, 48.71%) had TSH between 4.2 and 10 µiu/ml. Fourteen (35.89%) patients had a low TT4 and nine (23.07%) had low TT3 whereas FT3 was low in four (10.25%) and FT4 was low in three (7.6%) at presentation. In healthy volunteer group, none of the patients had abnormal thyroid function tests. Among NS group, eight patients had elevated anti-to whereas only two subjects in the control group had positive anti-to (p=0.3). None of the patients had TSH >15 µiu/ml and none were replaced with thyroxine. Table 1: Comparison of thyroid function tests between patients with nephrotic syndrome at diagnosis and healthy volunteers. Nephrotic syndrome patients at diagnosis (n=39) Controls (n=39) value Thyroid stimulating hormone 7.03± ±0.98 <0.001 (µiu/ml) Total triiodothyronine 97.46± ±18.63 <0.001 Total thyroxine (µg/dl) 7.37± ±1.42 <0.001 Free triiodothyronine 2.69± ±0.36 <0.001 Free thyroxine 0.85± ±0.12 <0.001 Age (years) 34.89± ± Male: Female 18:21 19: International Journal of Research in Medical Sciences October 2016 Vol 4 Issue 10 age 4301

3 atients with NS were followed-up over a period of 18.3±3.4 months. Eighteen patients had remission of NS at last follow-up whereas the rest had persistence of NS. At last follow-up, TSH was significantly lower whereas TT4, TT3, FT3 and FT4 were significantly higher when compared to that at diagnosis of NS. There was significant reduction in serum creatinine and spot urinary protein to creatinine ratio and significant increase in serum albumin in patients with remission of NS (Table 2). When patients with remission of NS were compared with those without remission, none of the characteristics at diagnosis of NS differed significantly between the two groups. When compared to characteristics at diagnosis of NS, patients with remission had significant decrease in spot urine protein creatinine ratio, serum creatinine and significant increase in serum albumin. At last follow-up, patients with remission had significantly lower TSH (p=<0.0001) and higher TT4 (p=<0.0001), TT3 (p=<0.0001), FT4 (p=0.0012) and FT3 (p=<0.0001) than those at diagnosis of NS. Among 18 patients with remission at last follow-up, five had elevated anti-to, three of whom continued to have TSH >10 µiu/ml whereas none among those with normal anti-to had TSH > 10 µiu/ml (p=0.012). Table 2: Comparison of patient characteristics at diagnosis of nephrotic syndrome and at last follow-up. Total triiodothyronine Total thyroxine (µg/dl) Free triiodothyronine Free thyroxine Thyroid stimulating hormone (µiu/ml) Spot urinary protein/creatinine Serum albumin (g/dl) Serum creatinine (mg/dl) Serum sodium (meq/l) At diagnosis of nephrotic syndrome At last follow-up value 97.46± ±15.62 < ± ± ± ± ± ± ± ± ± ±3.12 < ± ±0.8 < ± ±0.41 < ± ± Table 3: Comparison of characteristics between patients who achieved remission of nephrotic syndrome with those who did not. At diagnosis of nephrotic syndrome Remission at No remission at last follow-up last follow-up value* (n=18) (n=21) At last follow-up Remission at No remission last follow-up at last followup (n=18) (n=21) value* Total triiodothyronine 95.50± ± ± ±16.96 < Total thyroxine (µg/dl) 7.17± ± ± ± Free triiodothyronine 2.60± ± ± ± Free thyroxine 0.83± ± ± ± Thyroid stimulating hormone (µiu/ml) 7.67± ± ± ±3.78 < Spot urinary protein/creatinine 7.11± ± ± ± Serum albumin (g/dl) 2.01± ± ± ±0.22 <0.001 Serum creatinine (mg/dl) 1.55± ± ± ± Serum sodium (meq/l) ± ± ± ± * p value is for comparison between patients with and without remission at last follow-up DISCUSSION This study reports significantly lower concentration of serum TT4, TT3, FT3 and FT4 and significantly higher concentration of serum TSH in patients with NS when compared with age and sex matched healthy volunteers. revious studies have demonstrated similar findings. 4-7 Studies have also documented significant reduction in serum TBG levels. 12 Decrease in concentration of serum International Journal of Research in Medical Sciences October 2016 Vol 4 Issue 10 age 4302

4 TT4, TT3, FT3, FT4 and TBG levels in patients with NS is due to excessive urinary loss of these substances. 3-6 Urinary loss of serum T4, T3 and TBG levels in-turn lead to significant decrease in serum TT3 and TT4 and demands increased production of T4 from the thyroid gland to compensate for the urinary loss of T4 and T3. 4,5 This in turn increases serum TSH level. In milder cases, increase in TSH compensates to maintain serum FT3 and FT4 level. However, in severe urinary T4 loss, thyroid gland may not be able to meet for the increasing demand and FT4 level may fall below the normal range. In agreement with this, 58.97% of our patients had elevated TSH whereas only 7.6% of patients had low FT4. However, a larger number of patients demonstrate low serum TT4 level. Compared to 7.2% patients who had lower FT4, higher number (35.89%) of patients had low serum TT4, which is due to concomitant loss of TBG. The study also evaluated the thyroid functions at last follow-up in all patients and demonstrated that the abnormalities in thyroid function improved in most of the patients with remission of NS. Similar effect of remission of NS on thyroid functions has been reported previously. 3-5,10 Improvement in thyroid functions of NS patients has also been documented with bilateral nephrectomy which provides a cure for proteinuria and prevents loss of TBG and T4 in urine. 13 Anti-TO antibodies tended to be more common in NS patients than in control group. It may be a reflection of underlying autoimmune etiology of NS in these patients. Coexistence of autoimmune hypothyroidism has been described previously with various histological types of nephrotic syndrome, especially with membranous nephropathy In our study, four of 15 patients with membranous nephropathy had elevated anti-to antibodies. Among patients with remission elevated anti-to antibody was associated with persistence of hypothyroidism at last follow-up and these patients were initiated on LT4 replacement. Higher rate of progression to overt hypothyroidism in patients with positive anti microsomal antibodies has been proven previously. 19 Hence, patients with elevated anti-to should be closely followed-up for progression of hypothyroidism or initiated on LT4 replacement. CONCLUSION The study confirms that significant number of adult patients with NS have abnormalities in thyroid function tests. Most of these abnormalities improve with remission of NS. Anti-TO antibodies tend to be more common in adult NS patients than control group and those with elevated anti-to are more likely to progress to overt hypothyroidism. Hence, all patients with NS who have elevated TSH should be evaluated for anti-to and those with elevated anti-to should be closely followed-up or replaced with LT4. Funding: No funding sources Conflict of interest: None declared Ethical approval: The study was approved by the Institutional Ethics Committee REFERENCES 1. Musa BU, Seal US, Doe R. Excretion of corticosteroid-binding globulin, thyroxine-binding globulin and total protein in adult males with nephrosis: effects of sex hormones. J Clin Endocrinol Metab. 1967;27(6): Grymonprez A, roesmans W, Van Dyck M, Jans I, Goos G, Bouillon R. Vitamin D metabolites in childhood nephrotic syndrome. ediatr Nephrol. 1995;9(3): Fonseca V, Thomas M, Katrak A, Sweny, Moorhead JF. Can urinary thyroid hormone loss cause hypothyroidism? Lancet. 1991;338(8765): Afroz S, Khan AH, Roy DK. Thyroid function in children with nephrotic syndrome. Mymensingh Med J Jul;20(3): Ito S, Kano K, Ando T, Ichimura T. Thyroid function in children with nephrotic syndrome. ediatr Nephrol. 1994;8(4): Afrasiabi MA, Vaziri ND, Gwinup G, Mays DM, Barton CH, Ness RL, et al. Thyroid function studies in the nephrotic syndrome. Ann Intern Med. 1979;90(3): Oyemade OA, Lukanmbi FA, Osotimehin BO, Dada OA. Biochemical hypothyroidism in Nigerian children with nephrotic syndrome. Ann Trop aediatr. 1983;3(2): Finnegan JT, Slosberg EJ, ostellon DC, rimack WA. Congenital nephrotic syndrome detected by hypothyroid screening. Acta aediatr Scand. 1980;69(5): Dluholucký S, Hornová V, Hudec, Bucek M, Fukal J, Lukác. A case of congenital nephrotic syndrome detected during screening for congenital hypothyroidism. Cesk ediatr. 1982;37(4): Etling N, Fouque F. Effect of prednisone on serum and urinary thyroid hormone levels in children during the nephrotic syndrome. Helv aediatr Acta. 1982;37(3): Mattoo TK. Hypothyroidism in infants with nephrotic syndrome. ediatr Nephrol. 1994;8(6): Trouillier S, Delèvaux I, Rancé N, André M, Voinchet H, Aumaître O. Nephrotic syndrome: don't forget to search for hypothyroidism. Rev Med Interne. 2008;29(2): Chadha V, Alon US. Bilateral nephrectomy reverses hypothyroidism in congenital nephrotic syndrome. ediatr Nephrol. 1999;13(3): International Journal of Research in Medical Sciences October 2016 Vol 4 Issue 10 age 4303

5 14. Nishimoto A, Tomiyoshi Y, Sakemi T, Kanegae F, Nakamura M, Ikeda Y, et al. Simultaneous occurrence of minimal change glomerular disease, sarcoidosis and Hashimoto's thyroiditis. Am J Nephrol. 2000;20(5): Thajudeen B, John SG, Ossai NO, Riaz IB, Bracamonte E, Sussman AN. Membranous nephropathy with crescents in a patient with Hashimoto's thyroiditis: a case report. Medicine (Baltimore). 2014;93(8):e Ruiz-Zorrilla LC, Gómez GB, Rodrigo A, Molina MA. Membranous glomerulonephritis secondary to Hashimoto's thyroiditis. Nefrologia. 2010;30(5): Akikusa B, Kondo Y, Iemoto Y, Iesato K, Wakashin M. Hashimoto's thyroiditis and membranous nephropathy developed in progressive systemic sclerosis (SS). Am J Clin athol. 1984;81(2): Illies F, Wingen AM, Bald M, Hoyer F. Autoimmune thyroiditis in association with membranous nephropathy. J ediatr Endocrinol Metab. 2004;17(1): Rosenthal MJ, Hunt WC, Garry J, Goodwin JS. Thyroid failure in the elderly: microsomal antibodies as discriminant for therapy. JAMA. 1987;258: Cite this article as: Karethimmaiah H, Sarathi V. Abnormalities of thyroid function tests in adult patients with nephrotic syndrome. Int J Res Med Sci 2016;4: International Journal of Research in Medical Sciences October 2016 Vol 4 Issue 10 age 4304